I had the same problem. My LuLu proxy app disabled the networking. I booted the mbp in safe mode (holding shift while starting) and uninstalled LuLu. I found the uninstaller of Lulu in the application package. After that I removed lulu from the network profile settings and rebooted the laptop. Now is everything working fine.
JoepJ
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution